System to improve an ethernet network

ABSTRACT

A system to improve a Fiber Channel over Convergence Enhanced Ethernet (FCoCEE) network may include a sender in an FCoCEE network in which data packets having different data link layer structures are transmitted by the sender on a single data link. The system may also include a receiver to receive the data packets at the data link layer and to transmit an ACK and/or NAK in response to a sequence number in the data packets. The system may further include a replay buffer to retransmit the data packets where the replay buffer is sized by the length of the data link, data rate of the data link, the ACK and/or NAK processing time at either the sender and/or the receiver, and/or a threshold time for transmission and/or reception of the data packets.

BACKGROUND

The invention relates to the field of computer networking, and, moreparticularly, to computing networking.

The Fibre Channel over Ethernet (“FCoE”) standard was developed toenable the use of Fibre Channel over Ethernet networks. In addition, theConvergence Enhanced Ethernet (“CEE”) specification may include FCoE andbe referred to as FCoCEE.

SUMMARY

According to one example embodiment of the invention, a system toimprove an FCoCEE network may include a replay buffer to retransmit datapackets in a Fibre Channel over Convergence Enhanced Ethernet (FCoCEE)network in which data packets having different data link layerstructures are transmitted by a sender and received by a receiver at adata link layer. In this system, the receiver transmits an acknowledgesignal (ACK) and/or a no acknowledge signal (NAK) in response to asequence number in the data packets. Furthermore, the replay buffer issized by the length of a single data link, the ACK and/or NAK processingtime at either the sender and/or the receiver, and/or a threshold timefor transmission and/or reception of the data packets. The replay buffermay operate at the FCoCEE network's physical layer.

The system may further include a delimiter to indicate additionalreliable link layer sequence number bytes. If a reliable link layer isenabled, sequential Packet Sequence Numbers may be grouped together as acommon traffic class and/or given priority for this frame type and/orthis ACK type. The replay buffer may provide allocation to multiplepriority groups with link layer recovery enabled to avoid overflow.

The sender may modify the data packet's EtherType field so each datapacket comprises a sequence number. The receiver verifies and/or sendsan ACK and/or NAK based on sequence number comparison.

The replay buffer may resend unacknowledged data packets. The sender mayrefresh the sequence numbers and/or purge the replay buffer for datalink failure and/or data link recovery.

Another example aspect of the invention is a method to improve an FCoCEEnetwork. The method includes receiving at a receiver data packets havingdifferent data link layer structures on a single data link at the datalink layer via a sender through a Fibre Channel over ConvergenceEnhanced Ethernet (FCoCEE) and transmitting an ACK and/or NAK inresponse to a sequence number in the data packets. The method mayfurther include retransmitting the data packets via a replay buffer thatis sized by the length of the data link, the ACK and/or NAK processingtime at either the sender and/or the receiver, and/or a threshold timefor transmission and/or reception of the data packets.

The method may also include operating the replay buffer at the FCoCEEnetwork's physical layer. The method may further include modifying thedata packet's EtherType field so each data packet comprises a sequencenumber via the sender.

The method may additionally include indicating additional reliable linklayer sequence number bytes via a delimiter, and if a reliable linklayer is enabled, sequential Packet Sequence Numbers are groupedtogether as a common traffic class and/or given priority for this frametype and/or this ACK type. The method may also include verifying and/orsending an ACK and/or NAK based on sequence number comparison performedby the receiver. The method may further include resending unacknowledgeddata packets via the replay buffer and/or the sender refreshing thesequence numbers and/or purging the replay buffer for data link failureand/or data link recovery.

Another example aspect of the invention is computer readable programcodes coupled to tangible media to improve an FCoCEE network. Thecomputer readable program codes may be configured to cause the programto receive at a receiver data packets having different data link layerstructures on a single data link at the data link layer via a senderthrough the FCoCEE and transmit an ACK and/or NAK in response to asequence number in the data packets. The computer readable program codesmay further retransmit the data packets via a replay buffer that issized by the length of the data link, data rate of the link, the ACKand/or NAK processing time at either the sender and/or the receiver, anda threshold time for transmission and/or reception of the data packets.

The computer readable program codes may also operate the replay bufferat the FCoCEE network's physical layer. The computer readable programcodes may additionally modify the data packet's EtherType field so eachdata packet comprises a sequence number via the sender.

The computer readable program codes may also indicate additionalreliable link layer sequence number bytes via a delimiter, and if areliable link layer is enabled, sequential Packet Sequence Numbers aregrouped together as a common traffic class and/or given priority forthis frame type and/or this ACK type. The computer readable programcodes may additionally verify and/or send an ACK and/or NAK based onsequence number comparison via the receiver.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a system to improve an FCoCEEnetwork in accordance with an embodiment of the invention.

FIG. 2 is a flowchart illustrating method aspects according to anembodiment of the invention.

FIG. 3 is a flowchart illustrating method aspects according to themethod of FIG. 2.

FIG. 4 is a flowchart illustrating method aspects according to themethod of FIG. 2.

FIG. 5 is a flowchart illustrating method aspects according to themethod of FIG. 2.

FIG. 6 is a flowchart illustrating method aspects according to themethod of FIG. 2.

FIG. 7 is a flowchart illustrating method aspects according to themethod of FIG. 2.

FIG. 8 is a block diagram illustrating modifications to existing frametype in accordance with an embodiment of the invention.

FIG. 9 is a block diagram illustrating modifications to existing frameacknowledgment in accordance with an embodiment of the invention.

FIG. 10 is a block diagram of an exemplary approach to improve an FCoCEEnetwork in accordance with an embodiment of the invention.

DETAILED DESCRIPTION

The invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. Like numbers refer to like elementsthroughout.

With reference now to FIG. 1, a system 10 to improve an FCoCEE network12 is initially described. In one embodiment, the system 10 includes asender 14 in the FCoCEE network 12 in which data packets havingdifferent data link layer structures are transmitted by the sender on asingle data link 16. The system 10 also includes a receiver 18 in theFCoCEE network 12 that receives the data packets at a data link layerand transmits an ACK and/or NAK in response to a sequence number in thedata packets. The system 10 further includes a replay buffer 20 in theFCoCEE network 12 that retransmits the data packets where the replaybuffer is sized by the length of the single data link 16, data rate ofthe link, the ACK and/or NAK processing time at either the sender 14and/or the receiver 18, and/or a threshold time for transmission and/orreception of the data packets. The replay buffer may operate at theFCoCEE network's 12 physical layer.

In an embodiment, the system 10 further includes a delimiter 22 toindicate additional reliable link layer sequence number bytes. Inanother embodiment, if a reliable link layer is enabled, sequentialPacket Sequence Numbers may be grouped together as a common trafficclass and/or given priority for this frame type and/or this ACK type. Inanother embodiment, the replay buffer 20 provides allocation to multiplepriority groups with link layer recovery enabled to avoid overflow.

In an embodiment, the sender 14 modifies the data packet's EtherTypefield so each data packet comprises a sequence number. In anotherembodiment, the receiver 18 verifies and/or sends an ACK and/or NAKbased on a sequence number comparison.

In an embodiment, the replay buffer 20 resends unacknowledged datapackets. In another embodiment, the sender 14 refreshes the sequencenumbers and/or purges the replay buffer 20 for data link failure and/ordata link recovery.

Another aspect of the invention is a method to improve an FCoCEE network12 which is now described with reference to flowchart 24 of FIG. 2. Themethod begins at Block 26 and may include transmitting data packetshaving different data link layer structures on a single data link via asender in the FCoCEE network at Block 28. The method may also includereceiving at a receiver the data packets at the data link layer andtransmitting an ACK and/or NAK in response to a sequence number in thedata packets at Block 30. The method may further include retransmittingthe data packets via a replay buffer that is sized by the length of thedata link, data rate of the link, the ACK and/or NAK processing time ateither the sender and/or the receiver, and/or a threshold time fortransmission and/or reception of the data packets at Block 32. Themethod ends at Block 34.

In another method embodiment, which is now described with reference toflowchart 36 of FIG. 3, the method begins at Block 38. The method mayinclude the steps of FIG. 2 at Blocks 28, 30, and 32. The method mayfurther include operating the replay buffer at the FCoCEE network'sphysical layer at Block 40. The method ends at Block 42.

In another method embodiment, which is now described with reference toflowchart 44 of FIG. 4, the method begins at Block 46. The method mayinclude the steps of FIG. 2 at Blocks 28, 30, and 32. The method mayfurther include modifying the data packet's EtherType field so each datapacket comprises a sequence number via the sender at Block 48. Themethod ends at Block 50.

In another method embodiment, which is now described with reference toflowchart 52 of FIG. 5, the method begins at Block 54. The method mayinclude the steps of FIG. 2 at Blocks 28, 30, and 32. The method mayfurther include indicating additional reliable link layer sequencenumber bytes via a delimiter, and if a reliable link layer is enabled,sequential Packet Sequence Numbers are grouped together as a commontraffic class and/or given priority for this frame type and/or this ACKtype at Block 56. The method ends at Block 58.

In another method embodiment, which is now described with reference toflowchart 60 of FIG. 6, the method begins at Block 62. The method mayinclude the steps of FIG. 2 at Blocks 28, 30, and 32. The method mayfurther include verifying and/or sending an ACK and/or NAK based onsequence number comparison performed by the receiver at Block 64. Themethod ends at Block 66.

In another method embodiment, which is now described with reference toflowchart 68 of FIG. 7, the method begins at Block 70. The method mayinclude the steps of FIG. 2 at Blocks 28, 30, and 32. The method mayfurther include resending unacknowledged data packets via the replaybuffer and/or the sender refreshing the sequence numbers and/or purgingthe replay buffer for data link failure and/or data link recovery atBlock 72. The method ends at Block 74.

Another aspect of the invention is computer readable program codescoupled to tangible media to improve an FCoCEE network 12. The computerreadable program codes may be configured to cause the program totransmit data packets having different data link layer structures on asingle data link 16 via a sender 14 in the FCoCEE network 12. Thecomputer readable program codes may also receive at a receiver 18 thedata packets at the data link layer and transmit an ACK and/or NAK inresponse to a sequence number in the data packets. The computer readableprogram codes may further retransmit the data packets via a replaybuffer 20 that is sized by the length of the single data link 16, datarate of the link, the ACK and/or NAK processing time at either thesender 14 and/or the receiver 18, and a threshold time for transmissionand/or reception of the data packets.

In an embodiment, the computer readable program codes may also operatethe replay buffer 20 at the FCoCEE network's 12 physical layer. Inanother embodiment, the computer readable program codes may additionallymodify the data packet's EtherType field so each data packet comprises asequence number via the sender 14.

In an embodiment, the computer readable program codes may also indicateadditional reliable link layer sequence number bytes via a delimiter 22,and if a reliable link layer is enabled, sequential Packet SequenceNumbers are grouped together as a common traffic class and/or givenpriority for this frame type and/or this ACK type. In anotherembodiment, the computer readable program codes may additionally verifyand/or send an ACK and/or NAK based on sequence number comparison viathe receiver 18.

In view of the foregoing, the system 10 provides improved operation ofthe FCoCEE network 12. For example, Converged Fibre Channel overConverged Enhanced Ethernet (FCoCEE) networks do not define a mechanismto deliver the same level of data integrity as the networks they areintended to replace. As a result, system 10 provides a link layer retryfunction at the physical layer which is compatible with new FCoCEEfeatures.

In an embodiment, system 10 provides a replay buffer 20 at the sendingside of the link 16 that modifies the data link layer in a number ofways. In an embodiment, each data packet has a sequence number. Inanother embodiment, data packets are verified and acknowledged by thereceiver 18 (ACK Coalescing is allowed).

In an embodiment, the receiver 18 sends ACKs and NAKs, depending on thesequence number comparison. In another embodiment, the sender 14 timesunacknowledged packets and resends data packets.

In an embodiment, the size of the replay buffer 20 is determined by theneed to encompass the maximum length of the data link 16, data rate ofthe link, Ack/Nak processing time at both ends of the link, and maximumtransmission and reception times (the entire packet has to be receivedto verify the error checking, and sending the Ack/Nak packet may have towait on a Data Packet). For example, on a 10 G link, 100 meters, system10 estimated header overhead requires about 9 K bytes; for longerdistances the buffer may extend up to 32 K bytes. System 10 intends toavoid intersections with virtual lane (“VL”) buffers, which aretypically implemented in the inbound path and are used exclusively forflow control. In another embodiment, link reliability uses an outboundreplay buffer 20 to retransmit packets that never get to the VL buffers.

In an embodiment, system 10 provides a delimiter 22 to indicateadditional reliable link layer sequence number bytes. In anotherembodiment, system 10 modifies FCoCEE features such as priority flowcontrol and enhanced transmission selection (“ETS”) by recognizing ifthe reliable link layer is enabled. If so, system 10 groups sequentialPacket Sequence Numbers together as a common traffic class, and givespriority to this frame type and this ACK type. For multiple prioritygroups with link layer recovery enabled, system 10 will manage bufferallocation to avoid overflow.

System 10 provides a method and apparatus for implementing enhancedreliability at the link layer in a large CEE and/or FCoCEE convergednetwork 12. CEE and FCoCEE are new emerging protocols which modifytraditional Ethernet networks, in an effort to position Ethernet as thepreferred convergence fabric for all types of data center traffic. Themajor changes include the addition of credit based flow control at thephysical layer, congestion detection and data rate throttling, and theaddition of virtual lanes with quality of service differentiation.

The emergence of converged fabrics within future data centers isintended to enable architectures such as cloud computing, in whichmultiple server, storage, and other resources are commoditized andattached to a network which provides significant added functional value.This approach is also referred to as Converged Ethernet, Low LatencyEthernet, Enhanced Ethernet, or various other names.

The cloud computing approach is realized, in part, through Blade serversand storage enabled with converged top of rack (“TOR”) switches-. Inthis environment, there can be a significant number of switches within asingle data center, forming a very large network that rivals thecomplexity of the external long distance network.

It is important to note that CEE and FCoCEE do not employ TCP/IP, in aneffort to create a simpler, low cost approach that does not requireoffload processing or accelerators. Since converged fabrics are intendedto operate without the overhead of TCP/IP, they have effectively notransport level recovery built in and system 10 provides an enhancementwhich provides a more robust link layer in order to compensate for this.

Previous versions of the Ethernet standard relied on dropped or lostpackets to initiate recovery or retransmission of data, or on TCP/IP forend-to-end recovery. The bit error rate (“BER”) of such links has becomea limiting factor in the design of large networks with many switches,since each data packet needs to traverse more links in order to reachits destination. For example, a 10 Gbit/s Ethernet link in a 32 nodeswitch fabric may require 12 switches with 8 ports each, and a typicalpacket would undergo at least 4 hops between switches before reachingits destination. Since each data packet may need to traverse multiplelinks with more intra-switch hops in order to reach its destination,particularly if the data center fabric supports multiple server rackssharing a common service plane, the BER probability increases.Furthermore, the BER increases as data rates increase, since many linkpower penalties are proportional to data rate, and many convergednetworks will operate at 10, 40, or 100 Gbit/s data rates.

In order to address these concerns, an end to end link recoverymechanism has been proposed for layer 3-4 of the Ethernet stack.However, this approach depends on setting network timeout valuesproperly, which has several practical problems. Setting timeouts tooshort can cause a high number of retry attempts, which depletes serverand network resources, and this may also increase network congestion andprecipitate total fabric collapse. On the other hand, setting timeoutstoo low will also slow down recovery time and consequently reduce thethroughput of the network. Timeout values tend to increase in largernetworks, and they also increase in order to overcome local switchcongestion issues. End to end techniques also require multiple replaybuffers, one for each connection through the fabric. More complexrecovery schemes like forward error correction (“FEC”) codes requiresignificant overhead and only recover certain types of errors (do notfunction well in high BER environments).

System 10 provides a new technique in which a combination of sequencenumbers and timeout mechanisms at the end-to-end level are used forreliable link transmission. System 10 thus adds detection and recoveryto the converged fabric physical layer. This minimizes false retryattempts due to fabric congestion, and allows end to end timeout periodsto be significantly increased without affecting performance.

In system 10, link recovery is performed at the hardware layer by addinga replay buffer 20 to the transmitting node. This replay buffer 20 onlyneeds to be large enough to accommodate the data link 16 distance, datarate of the link, ACK/NAK processing time, and max MTU transmission andreception times. In an embodiment, the replay buffer 20 is a low cost,write-only buffer, e.g. a 10 Gbit/s link 100 m long with a 4 K payloadmay require about a 9 K buffer.

In an embodiment, each data packet has a sequence number, and thepackets are verified and acknowledged by the receiver 18 as they arrive.Depending on the sequence number comparison result, the receiver 18returns either an ACK or NAK response. In another embodiment, the sender14 times out unacknowledged packets and resends as required from itsreplay buffer 20. This feature could be implemented on all the links ina fabric, or it could be tied to the converged fabric service levels andonly implemented on some links in the fabric.

In an embodiment, system 10 adds information to existing fields in theCEE and/or FCoCEE packet header to indicate whether this feature isenabled. It allows backward compatibility with previous IEEE Ethernetstandards. This approach is expected to be faster and more robust thanthe alternatives, and can respond to any type of link degradation,including unusually high BER.

System 10 provides several distinct functions that could be implementedin a data center switch fabric to add reliability features at the linklevel. In an embodiment, system 10 improves link layer reliability byadding link layer retry. In another embodiment, bit errors are no longersurfaced to the end to end retry mechanism.

In an embodiment, end to end timeouts may be dramatically increased. Inanother embodiment, system 10 reduces false retries due to fabriccongestion. In another embodiment, system 10 extends the link layer byadding replay buffers 20 at the sending side, and adds a number of linklayer enhancements.

In an embodiment, system 10 readjusts the replay buffer's 20 size. Inanother embodiment, the replay buffer 20 needs to encompass the totallength of the data link 16, data rate of the link, Ack/Nak processingtime at both ends of the link, and maximum transmission and receptiontimes, e.g. the entire packet has to be received to verify the errorchecking, and sending the Ack/Nak packet may have to wait on a datapacket in some cases. As a typical example, a 10 Gbit/s link running 100meters may require about a 9 kbyte buffer.

In an embodiment, the replay buffer's 20 size is not necessarilydesigned for long links, but rather for larger switch fabrics withmultiple hops. The intention is to avoid intersection with flow controlbuffers used on the inbound path for long distance links. However, thisapproach could be adapted to long distance links, for example, thoserequired to extend the data center fabric over tens of kilometers fordisaster recovery.

In another embodiment, the system 10 adds a new delimiter 22 in the DCEheader field to indicate reliable link layer, e.g. should be no morethan two additional bytes, preferably located in an Ethertype field, butalternately included in start of frame (“SOF”) delimiter.

In an embodiment, the system 10 is built on top of existing hardwarestructure and link protocols. In another embodiment, the system 10 mayconfine new hardware to the Link Protocol Engine (LPE). In anotherembodiment, system 10 optionally using a hybrid scheme in which thesystem relies on selective retransmission as well as burstre-transmission (go back to N approach), which will not require in-orderACK/NAK transmission.

In an embodiment, system 10 could be used to improve performance oftightly coupled TOR switch solutions to server blades across a commonservice plane (the reliable link layer attributes could be tied toquality of service levels, set either by the switch or server). System10 could also provide enhanced reliability in proposed hybrid systemarchitectures utilizing a combination of System Z and Blade processorsinterconnected with an Ethernet fabric. This may be particularlyimportant when interconnecting traditionally high RAS (reliability,availability, and serviceability) platforms with most cost effectivecommodity platforms, without sacrificing link reliability.

It is noted that FCoCEE networks should maintain the same level of dataintegrity established by legacy data communication networks and biterror rates may be elevated in FCoCEE networks. It is also noted thatlarger data center networks (5000-10000 ports of 10 G, fullyprovisioned) typically require more switches, which implies each packetneeds to traverse more links, and this makes each packet moresusceptible to link bit errors.

TOR to core link data rates may be significantly higher than today(40-80 G), which makes data rate dependent noise worse and elevates biterror rates. In addition, encapsulation of FC data results in largerframes that are more prone to data corruption.

Currently, rapid end-to-end recovery is lacking. The only mechanismcurrently defined for Ethernet is timeouts, which get very long inlarger networks. Local switch fabric congestion further increasesrequired timeout values. Further, setting timeouts too short causesneedless retries that further increases congestion and can lead to totalfabric collapse, and setting timeouts too long slows recovery timecausing lower throughput.

In an embodiment, the system 10 provides improved link layer reliabilityby adding link layer retry at the physical layer. For example, biterrors are no longer surfaced to the end-to-end retry mechanism and thisminimizes end-to-end timeout intervals and false retries due to fabriccongestion.

In an embodiment, the system 10 extends the link layer by adding replaybuffers 20 at the sending side 14. In another embodiment, the linkreliability uses an outbound replay buffer 20 to retransmit packets thatnever get to the VL buffers. It is noted that link reliability can beindependent of VLs.

In an embodiment and with additional reference to FIG. 8, themodifications to existing frame type as used by system 10 are indicatedas reference callouts 76 and 78. As such, system 10 maintains backwardcompatibility with current frames.

In an embodiment and with additional reference to FIG. 9, themodifications to existing frame acknowledgement as used by system 10 areindicated by reference character 80. As such, system 10 maintainsbackward compatibility with current frames. In another embodiment,reliable link layer data flow of system 10 is illustrated in FIG. 10.

As will be appreciated by one skilled in the art, the invention may beembodied as a method, system, or computer program product. Furthermore,the invention may take the form of a computer program product on acomputer-usable storage medium having computer-usable program codeembodied in the medium.

Any suitable computer usable or computer readable medium may beutilized. The computer-usable or computer-readable medium may be, forexample but not limited to, an electronic, magnetic, optical,electromagnetic, infrared, or semiconductor system, apparatus, device,or propagation medium. More specific examples (a non-exhaustive list) ofthe computer-readable medium would include the following: an electricalconnection having one or more wires, a portable computer diskette, ahard disk, a random access memory (RAM), a read-only memory (ROM), anerasable programmable read-only memory (EPROM or Flash memory), anoptical fiber, a portable compact disc read-only memory (CD-ROM), anoptical storage device, or a magnetic storage device.

Computer program code for carrying out operations of the invention maybe written in an object oriented programming language such as Java,Smalltalk, C++ or the like. However, the computer program code forcarrying out operations of the invention may also be written inconventional procedural programming languages, such as the “C”programming language or similar programming languages.

The program code may execute entirely on the user's computer, partly onthe user's computer, as a stand-alone software package, partly on theuser's computer and partly on a remote computer or entirely on theremote computer or server. In the latter scenario, the remote computermay be connected to the user's computer through a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider).

The invention is described below with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of the invention. Itwill be understood that each block of the flowchart illustrations and/orblock diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions which execute on the computer or other programmableapparatus provide steps for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

It should be noted that in some alternative implementations, thefunctions noted in a flowchart block may occur out of the order noted inthe figures. For instance, two blocks shown in succession may, in fact,be executed substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionality involvedbecause the flow diagrams depicted herein are just examples. There maybe many variations to these diagrams or the steps (or operations)described therein without departing from the spirit of the invention.For example, the steps may be performed concurrently and/or in adifferent order, or steps may be added, deleted, and/or modified. All ofthese variations are considered a part of the claimed invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

While the preferred embodiment to the invention has been described, itwill be understood that those skilled in the art, both now and in thefuture, may make various improvements and enhancements which fall withinthe scope of the claims which follow. These claims should be construedto maintain the proper protection for the invention first described.

What is claimed is:
 1. A system comprising: a replay buffer, using areplay computer processor, to retransmit data packets in a Fibre Channelover Convergence Enhanced Ethernet (FCoCEE) network in which datapackets having different data link layer structures are transmitted by asender and received by a receiver at a data link layer; wherein thereceiver transmits at least one of an acknowledge signal (ACK) and a noacknowledge signal (NAK) in response to a sequence number in the datapackets; wherein the replay buffer is sized by at least one of length ofa single data link, data rate of the single data link, at least one ofACK and NAK processing time at either the sender or the receiver, and atleast one of a threshold time for transmission and reception of the datapackets; a delimiter to indicate additional reliable link layer sequencenumber bytes; wherein if a reliable link layer is enabled, sequentialPacket Sequence Numbers are at least one of grouped together as a commontraffic class and given priority for at least one of this frame type andthis ACK type; and wherein the sender modifies the data packet'sEtherType field so each data packet comprises a sequence number.
 2. Thesystem of claim 1 wherein the replay buffer operates at the FCoCEEnetwork's physical layer.
 3. The system of claim 1 wherein the replaybuffer provides allocation to multiple priority groups with link layerrecovery enabled to avoid overflow.
 4. The system of claim 1 wherein thereceiver at least one of verifies and sends at least one of an ACK andan NAK based on sequence number comparisons.
 5. The system of claim 1wherein the replay buffer resends unacknowledged data packets.
 6. Thesystem of claim 1 wherein the sender can refresh the sequence numbersand purge the replay buffer for at least one of data link failure anddata link recovery.
 7. A computer program product embodied in anon-transitory computer-readable medium comprising: computer readableprogram codes coupled to the tangible media to improve a Fibre Channelover Convergence Enhanced Ethernet (FCoCEE) network, the computerreadable program codes configured to cause the program to: receive at areceiver data packets having different data link layer structures on asingle data link at a data link layer via a sender through the FCoCEEand transmitting at least one of an acknowledge signal (ACK) and a noacknowledge signal (NAK) in response to a sequence number in the datapackets; retransmit the data packets via a replay buffer that is sizedby length of the single data link, data rate of the single data link,ACK and NAK processing time at either the sender or the receiver, and athreshold time for transmission and reception of the data packets; andindicate additional reliable link layer sequence number bytes via adelimiter, and if a reliable link layer is enabled, sequential PacketSequence Numbers are at least one of grouped together as a commontraffic class and given priority for at least one of this frame type andthis ACK type.
 8. The computer program product of claim 7 furthercomprising program code configured to: operate the replay buffer at theFCoCEE network's physical layer.
 9. The computer program product ofclaim 7 further comprising program code configured to: modify the datapacket's EtherType field so each data packet comprises a sequence numbervia the sender.
 10. The computer program product of claim 7 furthercomprising program code configured to: at least one of verify and sendat least one of an ACK and an NAK based on sequence number comparisonvia the receiver.